Skymaster Forum  

Go Back   Skymaster Forum > Messages
Register FAQ Members List Calendar Today's Posts

Reply
Thread Tools Rating: Thread Rating: 8 votes, 5.00 average. Display Modes
  #31  
Unread 07-19-13, 07:17 PM
captbilly captbilly is offline
Registered User
 
Join Date: Dec 2009
Location: Sacramento
Posts: 7
captbilly is on a distinguished road
Turbines burn a huge amount of fuel.

Quote:
Originally Posted by Skymaster337B View Post
The best diesel fuel engines are turbines. However, a turbo prop Skymaster is so cost prohibitive. Avgas engines are here to stay...until the unelected EPA outlaws 100LL.
Turbines have serious issues with specific fuel consumption (pounds per hp per hour). A typical small aircraft turbine will burn anywhere from 0.6 - 0.8 lbs per HP per hour, a TSIO-360 perhaps 0.5, but a diesel will burn as low as 0.3-0.35 lbs/HP per hour. That means your fuel burn at the same speed will be just about double using a turbine rather than a diesel. Even if the diesel were to weigh 500 lbs, while the turbine was at 300, you could go just as far at typical loads, and max range for the diesel would be double that of a turbine.

In addition, the specific fuel consumption of a turbine gets worse as you pull back the power. So putting in 2 750HP PT-6s would give outrageously poor fuel efficiency. Part of the reason that turbine aircraft need to fly so high to get reasonable range is that at high altitudes the engines can run at near 100% power without hitting very high IAS/CAS, which would cause a huge drag penalty. Diesels can have very high specific fuel consumption over a very large range of power settings, gasoline engines are good at lower power setting but very bad at maximum power.

I would love a diesel in my Skymaster, or Cessna 414A or anything else with a prop. The ability to use Jet-A or diesel fuel, simpler engine (no ignition system, or even a 2 stroke with no reliability issues), best possible specific fuel consumption, no icing, liquid cooling (though it could be air cooled), would all be great.
Reply With Quote
  #32  
Unread 07-19-13, 10:32 PM
jchronic jchronic is offline
Registered User
 
Join Date: Apr 2009
Location: Mass
Posts: 100
jchronic is on a distinguished road
Good article in the current AOPA magazine summarizing the status of diesels for GA airplanes. The takeaway (for me, anyway) is that either (1) you'd have to do a lot of flying to ever amortize the conversion with fuel savings, or (2) love your airplane so much you don't care how much money you spend on it - read 'sunk cost.'

Appears to me that diesels in Skymasters will remain in the category of 'an interesting academic discussion' for the forseeable future.

Joe
Reply With Quote
  #33  
Unread 07-20-13, 04:54 AM
captbilly captbilly is offline
Registered User
 
Join Date: Dec 2009
Location: Sacramento
Posts: 7
captbilly is on a distinguished road
You are almost certainly correct.

Quote:
Originally Posted by jchronic View Post
Good article in the current AOPA magazine summarizing the status of diesels for GA airplanes. The takeaway (for me, anyway) is that either (1) you'd have to do a lot of flying to ever amortize the conversion with fuel savings, or (2) love your airplane so much you don't care how much money you spend on it - read 'sunk cost.'

Appears to me that diesels in Skymasters will remain in the category of 'an interesting academic discussion' for the forseeable future.

Joe
I just wish that some still built a small pressurized twin that didn't cost several million dollars. Come to think of it, nobody makes a pressurized piston twin at all. I know that many people are comfortable flying behind a single engine but I think I have spent too much time flying multi-engine aircraft (much of it in 8 engine aircraft) that I just get nervous with one ( at least when the weather is bad or I am over really inhospitable terrain). To be honest, I have never had an engine failure in any aircraft except my old Skymaster, but it flew on like it was a non-event.

I love turbines, and most of my flying has been in jet aircraft, but they do suck down the gas. I remember burning more fuel taxiing to the runway in a t-38 than the total fuel capacity of my Glassair. I would love a 4-6 seat diesel pressurized twin that could fly at FL350 while burning 20gph even if it didn't have the smooth power of a turbine.
Reply With Quote
Reply



Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is Off
HTML code is Off
Forum Jump


All times are GMT -4. The time now is 08:01 PM.


Powered by vBulletin® Version 3.6.9
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.